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Synonyms

knee jerk

1 American  

noun

  1. a reflex extension of the leg, caused by contraction of the quadriceps, resulting from a sharp tap on the patellar tendon; patellar reflex.

knee-jerk 2 American  
[nee-jurk] / ˈniˌdʒɜrk /

adjective

  1. of or relating to a knee-jerk.

  2. Informal. reacting according to a certain habitual manner; unthinking.

    a knee-jerk liberal.
knee jerk British  

noun

  1. Also called: patellar reflex.  physiol an outward reflex kick of the lower leg caused by a sharp tap on the quadriceps tendon just below the patella

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

  1. made or occurring as a predictable and automatic response, without thought

    kneejerk support
"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of knee jerk1

First recorded in 1875–80

Origin of knee-jerk2

First recorded in 1895–1900

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

"Everyone recognizes there is a growing antibiotic resistance crisis, and the knee jerk reaction is to develop new antibiotics," You added.

From Science Daily • Feb. 22, 2024

Unite's deputy regional secretary, Davy Thompson, said minimum service levels are "the most invidious example of knee jerk legislating this country has seen in a long time".

From BBC • Jan. 13, 2024

“A sensible conversation is needed when balancing community safety with personal liberty. This is not a time for knee jerk responses,” he said.

From Seattle Times • Dec. 6, 2023

The sell-off was a "knee jerk reaction to an outcome that took a lot of people by surprise," Lotfi Karoui, chief credit strategist at Goldman Sachs, told Reuters.

From Reuters • Mar. 20, 2023

Anxious attention to the knee jerk inhibits it; gritting the teeth or clenching the fist reinforces it.

From Psychology A Study Of Mental Life by Woodworth, Robert S.

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.